Flowitem on the agv disappears unexpectedly

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Ryosuke S asked Jul 08 2021 at 11:31 AM Ryosuke S commented Jul 24 2021 at 10:56 AM

Flowitem on the agv disappears unexpectedly

I have set controlpoint at every corner, and I have set the agv to stop at those point by setting waypoints 'wait for defined delay time'. When agv convey flowitem from queue1 to queue2, when agv arrive at the cp marked '1', the flowitem disappear. But then when agv arrive at cp marked '2' the flowitem appear again. What is causing this?

test.fsm

Software Version:

FlexSim 21.0.6

agv controlpoint delaytime waypoint

capture032.jpg (166.4 KiB)

test.fsm (110.1 KiB)

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Joerg Vogel commented · Jul 08 2021 at 12:10 PM

There is more than only your flowitem disappearing. The involved token gets moved, too and as a result the AGV is not acquired anymore. There is something wrong with the internal logic, when you delay an AGV in combination with process flow, because the token in process flow does not know, what happens next if an external event delays the process flow. Obviously the token must be preempted and in an invisible process be delayed. And after finishing this invisible process the token must be reinstated back into the preempted process activity. That is not easy, because there are other interrupting processes like timetables or MTBF/MTTR tools, too.

I inserted a control process to keep track of tokens in the process. I assign colors to tokens and create a copy to push the token reference onto a list. By this I can keep a connection to the parent token. You will see that after returning, they don't apply to the task activity option to wait until complete. The tokens still reach the sink activity. What you have interpreted as a returning of an invisible gone item is infact a new transported item. The transported item is teleported into the destination queue. test_agv_waypoint_delay_Procees_flow_ts.fsm

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test-agv-waypoint-delay-procees-flow-ts.fsm (48.2 KiB)

Eric M commented · Jul 23 2021 at 10:26 PM

Hi @Ryosuke S, was my answer helpful? If so, please click the red "Accept" button at the bottom of the answer. Or if you still have questions, add a comment and we'll continue the conversation.

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Answer 1 · 2021-07-19T19:10:56Z

Eric M answered Jul 19 2021 at 7:10 PM Ryosuke S commented Jul 24 2021 at 10:56 AM

Hi @Ryosuke S Joerg is correct in that the token is continuing through the task sequence when the AGV is interrupted by the waypoint logic. Here's some info from the manual: "going forward we advise you to use process flow instead of Way Points for AGV control."

I added some process flow to your logic that will create a token when the AGV pre-arrives at the group I created called "Waypoints." The key here is creating a new task sequence with a higher priority than the original. Changing the preemption to "preempt only" will make it so the AGV will preempt its original task to delay, and then continue where it left off in the original task.

test1-em.fsm

test1-em.fsm (46.9 KiB)

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